Added a test case for bug #16504.

Results changed after the bug fix.

mysql-test/r/select.result

@@ -3388,5 +3388,5 @@ SELECT t2.sku, t2.sppr, t2.name, t1.sku, t1.pr
 FROM t2, t1 WHERE t2.sku=20 AND (t2.sku=t1.sku OR t2.sppr=t1.sku);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	const	PRIMARY	PRIMARY	4	const	1	
-1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	6	Using where
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	4	NULL	2	Using where
 DROP TABLE t1,t2;